Video Merging Orientation in Swift

Question

I am using video merging tutorial in that in ray wenderlich. I always get an 90 degree rotated video.When I add some different caffeine rotation codes my videos can t seen. Can you advise me I code that include CGAffineTransformMakeRotation.

My code is below

func orientationFromTransform(transform: CGAffineTransform) -> (orientation: UIImageOrientation, isPortrait: Bool) {
    var assetOrientation = UIImageOrientation.Up
    var isPortrait = false
    if transform.a == 0 && transform.b == 1.0 && transform.c == -1.0 && transform.d == 0 {
        assetOrientation = .Right
        isPortrait = true

    } else if transform.a == 0 && transform.b == -1.0 && transform.c == 1.0 && transform.d == 0 {
        assetOrientation = .Left
        isPortrait = true
    } else if transform.a == 1.0 && transform.b == 0 && transform.c == 0 && transform.d == 1.0 {
        assetOrientation = .Up

    } else if transform.a == -1.0 && transform.b == 0 && transform.c == 0 && transform.d == -1.0 {
        assetOrientation = .Down

    }
    return (assetOrientation, isPortrait)
}


func videoCompositionInstructionForTrack(track: AVCompositionTrack, asset: AVAsset) -> AVMutableVideoCompositionLayerInstruction {
    // 1
    let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
    // 2
    let assetTrack = asset.tracksWithMediaType(AVMediaTypeVideo)[0] as! AVAssetTrack

    // 3
    var transform = assetTrack.preferredTransform
    let assetInfo = orientationFromTransform(transform)
    var scaleToFitRatio = UIScreen.mainScreen().bounds.width / assetTrack.naturalSize.width

    if assetInfo.isPortrait {
        // 4
        print("ppppp")
        scaleToFitRatio = UIScreen.mainScreen().bounds.width / assetTrack.naturalSize.height
        let scaleFactor = CGAffineTransformMakeScale(scaleToFitRatio, scaleToFitRatio)

        //instruction.setTransform(t2, atTime: kCMTimeZero)


        instruction.setTransform(CGAffineTransformConcat(assetTrack.preferredTransform, scaleFactor),
            atTime: kCMTimeZero)




    } else {
        // 5
        let scaleFactor = CGAffineTransformMakeScale(scaleToFitRatio, scaleToFitRatio)
        var concat = CGAffineTransformConcat(CGAffineTransformConcat(assetTrack.preferredTransform, scaleFactor), CGAffineTransformMakeTranslation(0, UIScreen.mainScreen().bounds.width / 2))
        if assetInfo.orientation == .Down {
            print("down")
            let fixUpsideDown = CGAffineTransformMakeRotation(CGFloat(M_PI))
            let windowBounds = UIScreen.mainScreen().bounds
            let yFix = assetTrack.naturalSize.height + windowBounds.height
            let centerFix = CGAffineTransformMakeTranslation(assetTrack.naturalSize.width, yFix)
            concat = CGAffineTransformConcat(CGAffineTransformConcat(fixUpsideDown, centerFix), scaleFactor)
        }
        instruction.setTransform(concat, atTime: kCMTimeZero)
    }

    return instruction
}

score 1 · Accepted Answer · answered Feb 24 '16 at 18:00

A CGAffineTransformRotate operates around a point.

When you rotate the video, it "moves" around that point, including sometimes off the screen.

 x---    rotate 90 degrees clockwise around X becomes  -----x
 |   |                                                |     |
 |   |                                                 -----
 |   |
  ---

Not a great picture but you can see that if x is a fixed point, the video has actually moved.

Anyway, it's easy to fix - you're missing a Translate (literally moving the position of the video within the output frame).

Experiment with CGAffineTranslate (by the scale of the video) and you'll see the frame move around.

Good luck!

Video Merging Orientation in Swift

1 Answers1